Circles First Attempt

What is the formula for circumference of a circle given the diameter?

• C = π r

• C = 2 π r

• C = π d

• C = 2 π d

If the area of a circle is 25 π in² , then the diameter is?

• 10 in

• 5 in

• 25 in

• pi in

If the circumference of a circle is 22π , what is the diameter?

• 22 ft

• 11 ft

• π ft

• 0 ft

If the area of circle is 100 π , find the radius of the circle.

• 10 π

• 10

• 50

• 50 π

If you are given the diameter, how can you calculate the radius?

• Multiply the diameter by 2

• Divide the diameter by 2

• Add 2 to the diameter

• Subtract 2 from the diameter